The Volk Racing TE37 had an extremely successful 23 year run from 1996-2019. In this time span a surprising amount of variants have been created. Here is a brief history of variations:

TE37 MAG

Announced near the turn of the century in 1998, the TE37 MAG was a Magnesium Forged TE37 that was a close replica to the wheels used in Japan's Super GT race series (JGTC). The TE37 MAG only came in Magnesium Blue, a finish that gained it's lore with this wheel but has since skyrocketed in popularity (it's now an optional color for most Volk Racing wheels). These wheels were significantly lighter than the original TE37 but given the Magnesium Alloy mixture, but they also resulted in over a 80% price increase. Magnesium wheels are also harder to repair, so any damage typically resulted in a new wheel being required... this made the MAG a tougher sell and ultimately production only lasted a few years. 

TE37 Gravel

In 1999, only a few years after the release of the TE37, Rays had already seen their sales completely change with this new design. In order to support growth after the MAG, they released the TE37 Gravel to supply the TE37 to all racing segments. The Gravel featured robust features to handle high impact racing common in Rally racing: thick outer rim, reinforced spokes, and large barrels. Original size offerings came from 13 to 15 inch diameters; Bronze and White were offered, but the white ended up remaining as it stood up best to mud, dust, and dirt common in Rally racing. The Original Gravel came with OG TE37-esk decals, but over the years the design has slightly evolved with a new decal being introduced in the 2000's. 

To this day the TE37 Gravel is one of the oldest wheels in the Rays catalogue that hasn't had major structural changes.

TE37 Super Lap (TE37SL)

The Super Lap edition arose in the early 2000's as a bare-bones forged wheel. When it was released, the SL was a refresher for the TE37 that carried the same broad 6-spoke design. Using an 18x10.5 size as a bench mark, Rays was able to reduce 400 grams (0.88 lbs) of weight while adding strength. In order to do this they came up with a special light weight Pressed Graphite finish. The wheel is then machined on the lip and center portion to shave off weight where ever possible, this results in the SL not allowing center caps (unless you purchase a ring adapter). The Super Lap also have distinguishing red rim and spoke decals.

The TE37SL is still available to this day!

TE37 Tokyo Time Attack / LE37

Despite carrying different monikers, the TE37 Tokyo Time Attack and LE37 shared common elements. The LE37 should be first in terms of release, they were basically standard TE37 with a machined/diamond cut lip and included center caps. They stood for "Limited Edition TE37", they only came in Gunmetal or Gold and in certain sizes aimed at more premium vehicles. The TE37 Tokyo Time Attack came some time afterward and had similar treatment. They were only available in Black with the diamond cut lip, and had red accents. Initial version came with decals, but a rerelease introduced the machined logos as shown above. Both versions had limited runs and care considered among the rarer TE37 variants.

TE37 Large P.C.D.

Very early on Rays noticed a desire for TE37 wheels for large SUV and off-road vehicles. They took the 18-inch TE37 and reworked it for added strength (suitable for large SUV vehicles) and possibly off-road capabilities. The result is simply put, the Volk Racing TE37 Large P.C.D. The design has had little variance, but a few years ago they release the Progressive model. This refresh only features the machined logos in terms of physical changes. But the Progressive model also has a cliffed center,  reworked spokes, and a more rigid barrel, making it a much better and stronger wheel. The TE37 Large P.C.D. Progressive Model is still available to this day with applications for all sorts of large vehicles, including Domestic pick-up trucks...

TE37V / TE37V Mark-II

Few TE37 variants have created as much buzz and demand as the release of the TE37V. These wheels were released to accommodate Vintage and Classic Japanese vehicles which required small diameters and deep dishes, ergo the name: TE37 Vintage = TE37V. Initial release catered specifically to older vehicles, meaning sizes from 14-inch diameters to 17-inches. The initial offerings allowed you to order a 14x10 wheel with a 96 mm (nearly 4 inch) lip, something not available even from many 3-piece wheels. These wheels were so successful that demand for this style in larger diameters sparked the TE37V Mark-II which is basically the same design in 18-inch offerings. Deep dishes is still a requirement, so these wheels ended up being extremely popular in the resurgence of builds with wide-body and fender flares. To this day, the TE37V is one of the only deep dish monoblock forged wheels in the market.